YEAST ESS1, A CONSERVED PPIASE ESSENTIAL FOR MITOSIS

酵母和人类细胞需要ESS 1基因才能分裂。 该必需基因通过有丝分裂控制细胞周期进程， 考虑到其非凡的保护性， 真核生物 这项工作的目标是了解如何ESS 1 控制细胞周期。 酿酒酵母， 发现ESS 1的生物体将被用作模型 系统 ESS 1在结构和功能上都是高度保守的。 功能上;来自黑腹果蝇的ESS 1同源物， 人类拯救酵母ESS 1突变体。 Ess 1蛋白及其 对应物是唯一已知的同时含有WW 结构域和PPI酶（肽基-脯氨酰异构酶）结构域。 所述wwan 结构域是在蛋白质中发现的蛋白质-蛋白质相互作用模块 例如由人类肌肉萎缩症编码的肌营养不良蛋白 基因 PPIase结构域是一个催化模块，控制蛋白质的合成。 激酶、受体和转录因子的折叠和活性 在亲环素等蛋白质中发现， 免疫抑制药物。 这些域如何在2011年发挥作用， 控制细胞周期是未知的。 在这项提案中，酵母遗传学 将被用来了解BMP 1如何控制有丝分裂进程， WW和PPIase结构域如何促进该活性。 这 将通过（1）进行广泛的结构- 通过以下方法分析P11 WW和PPIase结构域的功能，（2） 分离ESS 1基因的条件等位基因，并将这些等位基因用于 细胞周期分析，以及（3）通过鉴定细胞周期的其他组分， ESS 1通路的抑制筛选和双杂交选择。 了解ESS 1在酵母中的功能将有助于 对有丝分裂调控途径知之甚少， 深入了解所有真核细胞的细胞周期控制。

Yeast and human cells require the ESS1 gene in order to divide. This essential gene controls cell cycle progression through mitosis, and given its extraordinary conservation, is probably required in all eukaryotes. The goal of this work is to understand how ESS1 controls the cell cycle. The yeast saccharomyces cerevisiae, the organism in which ESS1 was discovered, will be used as a model system. ESS1 is highly conserved both structurally and functionally; ESS1 homologs from Drosophila melanogaster and humans rescue yeast ess1 mutants. The Ess1 protein and its counterparts are the only known proteins to contain both a WW domain and a PPIase (peptidyl-prolyl isomerase) domain. The WW domain is a protein-protein interaction module found in proteins such as Dystrophin, encoded by the human muscular dystrophy gene. The PPIase domain is a catalytic module that controls the folding and activity of kinases, receptors and transcription factors and is found in proteins like cyclophilin that mediate the effects of immunosuppressive drugs. How these domains function in Ess1 to control the cell cycle is not known. In this proposal, yeast genetics will be used understand how Ess1 controls mitotic progression and how the WW and PPIase domains contribute to this activity. This will be accomplished by (1) conducting an extensive structure- function analysis of the Ess1 WW and PPIase domains, (2) by isolating conditional alleles of ESS1 gene and using these alleles for cell cycle analysis, and (3) by identifying other components of the ESS1 pathway using suppressor screens and tow-hybrid selections. An understanding of how ESS1 functions in yeast will illuminate poorly understood pathways of mitotic regulation and will provide insight into the control of the cell cycle in all eukaryotic cells.